JP2007113944A - Measuring instrument of viscoelasticity, and measuring method of viscoelasticity - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To measure the viscoelastic characteristics of a viscoelastic material used in a pressure-sensitive adhesive or the like, within a wide range of strain with higher accuracy. <P>SOLUTION: The upper and lower ends of a test piece 1 are held by an upper chuck 13 and a lower chuck 14. The upper chuck 13 is connected to the upper bean 11 of this measuring instrument of viscoelasticity, and the lower chuck 14 is connected to the exciter 17 provided to the lower beam 18 of the measuring instrument. The upper beam 11 of the measuring instrument is moved at a predetermined speed or at a predetermined strain speed by a drive motor 19 and the exciter 17 is driven, while giving static displacement to the sample piece 1 to apply dynamic displacement to the sample piece 1. The static load produced in the sample piece 1 is detected by a static load sensor 12, and the dynamic displacement and the dynamic load are detected at the same position and at the same time by a composite sensor 15 by using an impedance head or the like. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an apparatus and method for measuring viscoelastic properties of a sample. In particular, the present invention relates to a viscoelasticity measuring apparatus and method for measuring viscoelasticity characteristics of a viscoelastic body having nonlinear characteristics under large deformation.

  A commercially available viscoelasticity measuring device is a device that mainly measures viscoelasticity characteristics in a linear deformation range of a sample, and can measure only a strain within a few hundred% even if the dimensions of the sample are devised. However, in polymer viscoelastic bodies used for pressure-sensitive adhesives and adhesives, a large number of molecular chains form a network structure with various crosslink densities by chemical crosslinks or physical crosslinks. Alternatively, measurement of viscoelastic properties within a strain of several hundred percent is insufficient for evaluating product development, design, manufacturing, processing, distribution, and the like.

On the other hand, as a viscoelasticity measuring apparatus for measuring the nonlinear viscoelasticity characteristics of a viscoelastic body sample, an apparatus for measuring a stress-strain curve and simultaneously measuring viscoelasticity has been proposed (see Patent Document 1).
Japanese Patent No. 3620959

  In the apparatus described in Patent Document 1, a stress-strain curve and a complex elastic modulus are simultaneously measured by applying sinusoidal vibration (dynamic displacement) by a vibrator while applying stretching deformation (static displacement) to a sample. ing. However, in this apparatus, a strain meter that measures dynamic displacement and a load meter that measures dynamic load are arranged on opposite sides of the sample to be stretched, and are detected by separate sensors. For this reason, in the detection of dynamic displacement and dynamic load, due to the position difference between sensors, the detection value is affected by differences in the measurement environment such as temperature and humidity, as well as effects such as inertial force, time difference, and phase difference. May appear.

  In the apparatus of Patent Document 1, the static load and the dynamic load are measured using the same load meter, the static load is detected as a DC component from the load meter, and the dynamic load is detected as an AC component. That is, the signal from the load cell is separated and processed as an AC component and a DC component by an AC / DC component separation circuit. Therefore, the dynamic load detection system and the dynamic displacement detection system have different frequency characteristics. For these reasons, viscoelasticity cannot be measured with high accuracy by a conventional apparatus.

  Furthermore, in a viscoelasticity measuring apparatus that applies a dynamic displacement with a vibrator while applying a static displacement, it is necessary to prevent fluctuations in the vibration center position of the vibrator due to a static tensile force. For example, in the apparatus of Patent Document 1, the origin of the shaker is adjusted by feeding back the DC component of the output from the load detection system to the control system of the shaker.

  However, in the method of Patent Document 1, since the origin adjustment of the shaker extends over the two processing systems of the load detection system and the shaker control system, when the load changes abruptly, the shaker is delayed due to a time delay. Hunting may occur in the origin adjustment. In addition, if two processing systems are used for the origin adjustment of the shaker, if there is a malfunction such as an operation error or function deterioration in one of the processing systems, the origin adjustment of the shaker will not function, and the vibration center position will be within the allowable range. There is a high possibility that the vibrator will be damaged.

  This invention is made | formed in view of the said problem, and makes it a subject to measure a viscoelastic characteristic more accurately in the wide strain range. Still another object of the present invention is to improve the reliability of the vibrator origin adjustment processing in the viscoelasticity measuring apparatus and reduce the possibility of damage to the vibrator.

  (1) A viscoelasticity measuring apparatus according to claim 1 of the present invention is a static displacement means for applying a static displacement to a sample piece, and a dynamic displacement for the sample piece while the static displacement is applied to the sample piece. , A static load sensor that detects a static load generated on the sample piece, a dynamic displacement sensor that detects a dynamic displacement applied to the sample piece, and a dynamic load generated on the sample piece A dynamic load sensor, wherein the static load sensor and the dynamic load sensor are separate and independent sensors.

  (2) In the viscoelasticity measuring apparatus according to claim 2, the dynamic displacement sensor and the dynamic load sensor are configured as a composite sensor that simultaneously detects the dynamic load and the dynamic displacement at the same position.

  (3) In the viscoelasticity measuring apparatus according to claim 3, an impedance head is used for the composite sensor.

  (4) The viscoelasticity measuring apparatus according to claim 4 includes a position sensor for detecting a center position of vibration given by the shaker, and feeds back a signal from the position sensor to the control of the shaker. Hold the position in place.

  (5) In the viscoelasticity measuring apparatus according to claim 5, the sample used for the sample piece is a polymer viscoelastic body, and the viscosity of the polymer elastic body during or after stretching of the sample piece is stretched. Measure elastic properties.

  (6) In the viscoelasticity measuring apparatus according to claim 6, the polymer viscoelastic body is a viscoelastic body used for a pressure-sensitive adhesive or a visco-adhesive.

(7) In the viscoelasticity measuring apparatus according to claim 7, the viscoelastic characteristics of the sample piece are such that the sample piece is stretch-deformed under the conditions of a strain rate of 0.001 to 5 s ⁻¹ and a strain of 100% or more, or Measured after stretch deformation.

  (8) In the viscoelasticity measuring apparatus according to claim 8, the viscoelastic characteristics of the sample piece are measured under a condition where the strain is 300% or more.

  (9) According to a ninth aspect of the present invention, there is provided a viscoelasticity measuring apparatus according to a ninth aspect of the present invention, wherein a static displacement means for applying a static displacement to a sample piece, An exciter that applies displacement, a static load sensor that detects a static load generated on the sample piece, a dynamic displacement sensor that detects a dynamic displacement applied to the sample piece, and a dynamic load generated on the sample piece The dynamic displacement sensor and the dynamic load sensor detect the dynamic load and the dynamic displacement at the same position at the same time.

  (10) The viscoelasticity measuring method according to claim 10 of the present invention is characterized by using the apparatus according to claims 1 to 9.

  As described above, according to the present invention, viscoelastic characteristics can be measured with higher accuracy in a wide strain range. Furthermore, according to the present invention, the reliability of the vibrator origin adjustment process in the viscoelasticity measuring device can be improved, and the possibility that the vibrator is damaged can be reduced.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram of a viscoelasticity measuring apparatus according to an embodiment of the present invention.

  The viscoelasticity measuring apparatus 10 of the present embodiment is an apparatus that accurately and stably measures viscoelasticity under large deformation of a sample such as a polymer viscoelastic body used for an adhesive or an adhesive, for example. Measurement is performed over a wide strain range of several hundred to several thousand percent.

  The upper and lower ends of the viscoelastic body sample 1 having nonlinear viscoelastic characteristics are sandwiched between the upper chuck 13 and the lower chuck 14, respectively. The upper chuck 13 is connected to the upper beam 11 of the apparatus, and a static load sensor 12 is attached to the connecting portion. The upper beam 11 of the apparatus is moved at a predetermined speed or a predetermined strain speed in either the upper or lower direction while being controlled in speed by the drive motor 19, and gives a static load or static displacement to the sample 1. The drive motor 19 is driven and controlled by a motor driver 28, and the motor driver 28 is controlled by, for example, a personal computer 21 via an interface 22 including an A / D converter (not shown).

  On the other hand, the lower chuck 14 is connected to a vibration exciter 17 installed on the apparatus lower beam 18, and a composite sensor 15 is attached to the connecting portion. The vibrator 17 gives a dynamic displacement (sinusoidal vibration) to the sample 1 that is statically deformed by the movement of the beam 11 on the apparatus. Further, the vibration exciter 17 is driven and controlled by a signal from the power amplifier 27 as will be described later.

  The static load sensor 12 is a sensor that detects a static load generated on the sample 1. A signal from the static load sensor 12 is amplified by the load amplifier 23 and input to the personal computer 21 via the interface 22, for example.

  On the other hand, the composite sensor 15 is a sensor that directly detects a dynamic load and a dynamic displacement due to sinusoidal vibration simultaneously and at the same position. Signals related to the load and displacement detected by the composite sensor are amplified by the two-channel amplifier 24 and input to the personal computer 21 via the interface 22. For example, an impedance head is used as the composite sensor 15, but the present invention is not limited to this. When an impedance head is used for the composite sensor 15, for example, a 2-channel charge amplifier is used for the 2-channel amplifier 24.

  In the present embodiment, the viscoelasticity measuring device 10 is provided with a position sensor 16 for detecting the center position of sinusoidal vibration given by the vibration exciter 17. A signal from the position sensor 16 is amplified by the position amplifier 25 and is input to the shaker vibration center position holding circuit 26. Based on the position signal from the position sensor 16, the shaker vibration center position holding circuit 26 feeds back to the control system of the shaker 17 in order to prevent the vibration center position of the shaker 17 from deviating from the origin. It is a circuit that performs. That is, the power amplifier 27 that drives and controls the shaker 17 is feedback-controlled based on the control signal from the personal computer 21 and the signal from the shaker vibration center position holding circuit 26, thereby causing sine vibration to the sample 1. While being applied, the vibration center of the vibrator 17 is held at the origin position.

  Note that the static displacement amount of the sample 1 is obtained by a drive amount of the drive motor 19 or a displacement meter attached to the viscoelasticity measuring apparatus 10.

  Hereinafter, operation | movement of the viscoelasticity measuring apparatus 10 of this embodiment is demonstrated. By controlling the drive of the drive motor 19, the upper beam 11 of the apparatus is moved upward to give a static displacement to the sample 1. At the same time, the vibrator 17 is driven to give the sample 1 a dynamic displacement due to a predetermined sine vibration.

  The static displacement amount of the sample 1 is calculated from the control speed and control time (drive amount of the drive motor) of the upper beam 11 of the apparatus, the static load is obtained from the signal detected by the static load sensor 12, and the stress-strain curve is obtained. Ask for. In parallel with the detection of the static viscoelastic characteristics, the dynamic displacement amount and the dynamic load of the sample 1 are obtained based on the signal from the composite sensor 15 via the two-channel amplifier 24, and the sample 1 The complex elastic modulus, complex compliance, loss tangent, etc. showing the dynamic viscoelastic properties are obtained.

  Further, during the measurement operation of the static viscoelasticity and the dynamic viscoelasticity, the position shift of the vibration center caused by the static load is monitored by the position sensor 16, and the position sensor 16 is passed through the shaker vibration center position holding circuit 26. Is fed back to the power amplifier 27 to control the drive of the vibrator 17 so that the center of vibration is held at the origin position of the vibrator 17.

  The quantities related to the static viscoelasticity and the dynamic viscoelasticity described above are calculated by the personal computer 21 and recorded on a recording medium attached to the personal computer 21.

As described above, in the viscoelasticity measuring apparatus according to the present embodiment, the dynamic displacement and the dynamic load are detected simultaneously and at the same position using the composite sensor while the sample is stretched. The problem of phase shift with a static load can be solved, and viscoelastic characteristics can be measured accurately and stably over a wide strain range including when the sample is largely deformed. For example, viscoelastic characteristics (particularly dynamic) of a sample (particularly a polymer viscoelastic body) during or after stretching deformation with strain of 100% or more (particularly preferably 300% or more) at a strain rate of 0.001 to 5 s ⁻¹ . (Viscoelastic properties) can be accurately measured. Here, the strain rate is obtained by dividing the static displacement rate by the length of the sample at the moment during the stretching deformation.

In this embodiment, since the sensor for detecting the dynamic displacement and the sensor for detecting the dynamic load detect the dynamic displacement and the dynamic load directly at the same position at the same time, the dynamic displacement and the dynamic load are detected. There is no difference in detection time between dynamic loads. Further, in the personal computer 21, the inertial force of the sample 1 and the lower chuck 14 that has been measured in advance is subtracted from the dynamic load detected by the sensor that detects the dynamic load. Calculate the true value of the dynamic load. To explain the specific method for calculating a dynamic load detected by the dynamic load sensor, considering the phase difference between the dynamic displacement can be represented by f _o shown in FIG. Accordingly, the real part of f _o is f _o ', the imaginary part f _o ", the phase difference between the dynamic displacement and dynamic loads f alpha _o and expressed. In addition, considering the inertia term f _i by the inertial force Then, the dynamic load f generated in the sample 1 excluding the influence of the inertial force and the phase difference α between the dynamic displacement excluding the influence of the inertial force and the dynamic load f are expressed as follows.
f = √ ((f _o '−f _i ) ² + (f _o ″) ² )
α = tan ⁻¹ (f _o ″ / (f _o '−f _i ))
That is, there is no detection time difference between the dynamic displacement and the dynamic load, and the dynamic displacement f and the dynamic load excluding the influence of the dynamic load f and the inertial force generated in the sample 1 excluding the influence of the inertial force. Since the phase difference α with respect to f is corrected and calculated, the accuracy is further improved. Furthermore, in this embodiment, since a dedicated position sensor for detecting the vibration center position of the shaker is provided, the reliability of the shaker origin adjustment process can be improved and the shaker can be damaged. Can be reduced.

  Note that the positional relationship among the sample 1, the static load sensor 12, the composite sensor 15, and the vibration exciter 17 is arbitrary, and is not limited to the arrangement of the present embodiment. That is, the static load sensor 12 may be disposed on the side of the vibrator 17 with respect to the sample 1 together with the composite sensor 15, and conversely, the composite sensor 15 applies to the sample 1 together with the static load sensor 12. You may arrange | position on the opposite side (device upper beam 11 side) of the vibrator 17. It is also possible to exchange the arrangement of the static load sensor 12 and the composite sensor 15.

  Next, referring to Table 1 and FIGS. 3 and 4, the viscoelasticity measuring apparatus according to the present embodiment is compared with the comparative example using the viscoelasticity measuring apparatus according to the related art. The actual effect in an elasticity measuring apparatus is shown.

Example 1 and Comparative Example 1 show the effect of this embodiment by performing dynamic load measurement and dynamic displacement measurement at the same position. In Example 1 and Comparative Example 1, 1 part of an isocyanate-based crosslinking agent was used for 100 parts of an acrylic pressure-sensitive adhesive (a copolymer of butyl acrylate: acrylic acid = 91: 9, Mw = 8.2 × 10 ⁵ ). A partially added adhesive was used as a sample. The pressure-sensitive adhesive was applied to the release material so that the film thickness after drying was 25 μm, dried with hot air, and then allowed to stand at room temperature for 7 days for adjustment. In Example 1 and Comparative Example 1, this pressure-sensitive adhesive was laminated and cut to prepare three sample pieces a to c having different effective lengths, and a viscoelasticity measurement test was performed on each of them.

  The sample piece a has a width of 3 mm, an effective length of 10 mm, and a thickness of 3 mm, and the sample piece b has a width of 3 mm, an effective length of 15 mm, and a thickness of 2 mm. The sample piece c has a width of 3 mm, an effective length of 20 mm, and a thickness of 1.5 mm. That is, the sample pieces a, b, and c were prepared as three bulk adhesive samples having the same mass and width and different effective lengths.

Sample Example a (100 mm / min) for both Example 1 (viscoelasticity measuring device of the present embodiment; configuration of FIG. 1) and Comparative Example 1 (conventional viscoelasticity measuring device; configuration of FIG. 1 described in Patent Document 1) , Sample piece b (150 mm / min), sample piece c (200 mm / min), initial strain rate in each sample piece: 0.167 s ⁻¹ , excitation frequency: 16 Hz Bulk adhesive sample piece a, b , C were subjected to a viscoelasticity measurement test. Table 1 shows loss tangent values for the sample pieces a, b, and c when the strain reaches 1000%. Each sample piece a, b, and c was measured five times, and Table 1 shows the average value. The error between the measurement data of each measurement test was about 5% with almost no difference between the apparatuses of Example 1 and Comparative Example 1.

  As shown in Table 1, in Example 1 using the viscoelasticity measuring apparatus of the present embodiment, the loss tangent values of the sample pieces a, b, and c having different effective lengths are substantially equal, and the sample piece There was no effect on the measured value due to the difference in the effective length. On the other hand, in Comparative Example 1 using the conventional viscoelasticity measuring device, the loss tangent value decreases (16% from a to c) as the effective length of the sample piece increases, and the measurement error is considered. It is clear that the difference in the effective length of the sample piece affects the measured value.

  That is, in the first comparative example using the conventional viscoelasticity measuring apparatus in which the dynamic load measurement and the dynamic displacement measurement are performed at different positions with the sample piece interposed therebetween, it takes time to propagate the dynamic displacement. A time difference (phase difference) occurs in detection between the sensors. However, in Example 1 using the viscoelasticity measuring apparatus of the present embodiment, the sensor for detecting the static load and the dynamic load is separated and independent, and the measurement of the dynamic load and the measurement of the dynamic displacement are performed simultaneously at the same position. Since it is configured to be integrated and can be performed, the occurrence of such a problem can be prevented. The error due to the propagation time of the dynamic displacement increases as the length of the sample piece is extended, but according to Example 1 to which the present embodiment is applied, the error is caused by the difference in the effective length of the sample piece. Therefore, it is possible to measure the viscoelastic characteristics of the sample with high accuracy even under large deformation.

  On the other hand, in the second embodiment (configuration shown in FIG. 1) and the second comparative example (configuration shown in FIG. 1 described in Patent Document 1), an excitation control system is used to prevent hunting from occurring in the vibrator origin adjustment processing. This shows the effect of this embodiment by providing a position sensor for detecting a dedicated vibration center that directly performs feedback processing.

In Example 2 and Comparative Example 2, the sample piece a in Example 1 and Comparative Example 1 was used as a sample. The test was performed in each of Example 1 and Comparative Example 1 at a static displacement rate of 100 mm / min (initial strain rate: 0.167 s ⁻¹ ) and 1000 mm / min (initial strain rate: 1.667 s ⁻¹ ). The presence or absence of hunting at this time was inspected. In Example 2, hunting did not occur at any static displacement speed. On the other hand, in Comparative Example 2, hunting did not occur when the static displacement rate was 100 mm / min (initial strain rate: 0.167 s ⁻¹ ), but 1000 mm / min (initial strain rate: 1.667 s ^{−). In case of 1} ), damping hunting occurred.

  That is, in Comparative Example 2 using the conventional viscoelasticity measuring device, the adjustment of the origin center position of the vibration exciter is straddled across the two processing systems, and the position is indirectly detected through the load. Therefore, hunting has occurred when the load changes suddenly due to a time delay of feedback or the like. On the other hand, in Example 2 using the viscoelasticity measuring apparatus of the present embodiment, since the feedback processing is directly performed from the position sensor dedicated for position measurement to the excitation control system, the time delay does not occur. , Hunting can be effectively prevented.

  Next, Embodiment 3 will be described with reference to FIGS. Example 3 shows an example of viscoelastic characteristics over a wide strain range including large deformation of a plurality of samples, and was measured using the viscoelasticity measuring apparatus of the present embodiment.

In Example 3, an isocyanate-based crosslinking agent was added at a different ratio to 100 parts of an acrylic pressure-sensitive adhesive (a copolymer of butyl acrylate: acrylic acid = 91: 9, Mw = 8.2 × 10 ⁵ ). Then, a plurality of samples having different cross-linking agent addition amounts were prepared. That is, pressure-sensitive adhesive samples to which 0.25 part, 1 part, 2 parts, and 4 parts of an isocyanate-based additive were added were prepared, formed into a thickness of 2 mm, a width of 3 mm, and an effective length of 10 mm, and then bulk adhesive. Sample pieces d, e, f, and g were used. The pressure-sensitive adhesive was applied to the release material so that the film thickness after drying was 25 μm as in Examples 1 and 2 and Comparative Examples 1 and 2, dried with hot air, and then allowed to stand at room temperature for 7 days. Cut and adjusted.

The measurement was performed at a static displacement rate of 100 mm / min (initial strain rate: 0.167 s ⁻¹ ) and an excitation frequency of 16 Hz. The test was performed five times for each sample, and the complex elastic modulus and loss tangent were measured. 3 and 4 show average values of data obtained by five measurements.

  FIG. 3 is a graph showing the relationship between strain (horizontal axis) and complex elastic modulus (vertical axis) of sample pieces d to g, and FIG. 4 shows the relationship between strain (horizontal axis) and loss tangent (vertical axis). It is a graph to show. 3 and 4 show changes in the complex elastic modulus (Pa) and loss tangent (-) of the respective sample pieces d to g when the strain is 0% to 2500%.

  As shown in FIGS. 3 and 4, the dynamic viscoelastic behavior shows almost no difference between the samples when the strain measurable with a commercially available viscoelasticity measuring apparatus is 100% or less. I can't. However, as strain increases (during large deformation), the behavior of dynamic viscoelasticity varies greatly between samples. Therefore, it is important to measure the dynamic viscoelastic characteristics of a specimen when it is deformed with high accuracy without degrading the accuracy of product development, design, manufacturing, processing, distribution, etc. According to the embodiment, this can be achieved.

It is a block diagram of the viscoelasticity measuring apparatus which is one Embodiment of this invention. It is a graph which shows the vector of the dynamic load and inertia force which arise in a sample piece. It is a graph which shows the relationship between the distortion (horizontal axis) of a sample piece, and a complex elastic modulus (vertical axis). It is a graph which shows the relationship between distortion (horizontal axis) and loss tangent (vertical axis).

Explanation of symbols

1 Sample (sample piece)
DESCRIPTION OF SYMBOLS 10 Viscoelasticity measuring apparatus 11 Upper beam 12 Static load sensor 13 Upper chuck 14 Lower chuck 15 Composite sensor 16 Position sensor 17 Exciter 18 Lower beam 19 Drive motor 21 Personal computer 22 Interface 23 Load amplifier 24 Two channel amplifier 25 Position amplifier 26 Exciter vibration center position holding circuit 27 Power amplifier 28 Motor driver

Claims (10)

Static displacement means for imparting a static displacement to the sample piece;
While applying the static displacement to the sample piece, a vibrator for applying a dynamic displacement to the sample piece;
A static load sensor for detecting a static load generated in the sample piece;
A dynamic displacement sensor for detecting a dynamic displacement applied to the sample piece;
A dynamic load sensor for detecting a dynamic load generated in the sample piece,
The viscoelasticity measuring apparatus, wherein the static load sensor and the dynamic load sensor are separate and independent sensors.   The viscoelasticity measurement according to claim 1, wherein the dynamic displacement sensor and the dynamic load sensor are configured as a composite sensor that simultaneously detects the dynamic load and the dynamic displacement at the same position. apparatus.   The viscoelasticity measuring apparatus according to claim 2, wherein an impedance head is used for the composite sensor.   A position sensor for detecting a center position of vibration applied by the shaker; a signal from the position sensor is fed back to the control of the shaker, and the center position is held at a predetermined position. The viscoelasticity measuring device according to any one of claims 1 to 3.   2. The sample used for the sample piece is a polymer viscoelastic body, and the viscoelastic property of the polymer elastic body is measured during or after stretching of the sample piece. The viscoelasticity measuring apparatus according to any one of claims 4 to 5.   The viscoelasticity measuring apparatus according to claim 5, wherein the polymer viscoelastic body is a viscoelastic body used for an adhesive or an adhesive. The viscoelastic property of the sample piece is measured during or after stretching deformation under the condition that the sample piece has a strain rate of 0.001 to 5 s ⁻¹ and a strain of 100% or more. Item 7. The viscoelasticity measuring device according to Item 6.   The viscoelasticity measuring apparatus according to claim 7, wherein the viscoelastic characteristics of the sample piece are measured under a condition where the strain is 300% or more. Static displacement means for imparting a static displacement to the sample piece;
While applying the static displacement to the sample piece, a vibrator for applying a dynamic displacement to the sample piece;
A static load sensor for detecting a static load generated in the sample piece;
A dynamic displacement sensor for detecting a dynamic displacement applied to the sample piece;
A dynamic load sensor for detecting a dynamic load generated in the sample piece,
The viscoelasticity measuring apparatus, wherein the dynamic displacement sensor and the dynamic load sensor detect the dynamic load and the dynamic displacement simultaneously at the same position.   A viscoelasticity measuring method using the apparatus according to claim 1.

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